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Header in .NET Create barcode 128 in .NET Header

Header generate, create code 128 code set b none on .net projects USPS PLANET Barcode Nothing FIGURE 15.11. Skip L ist With Links 2 Nodes Ahead (Level 1).

. Skip Lists and so on. The probl em with this scheme is that when we insert or delete a node, we have to rearrange a tremendous number of node pointers, making our skip list much less ef cient. The solution to this problem is to allocate nodes to the link levels randomly.

The rst node (after the header) might be a level 2 node, whereas the second node might be a level 4 node, the third node a level 1 node again, and so on. Distributing link levels randomly makes the other operations (other than search) more ef cient, and it doesn t really affect search times. The probability distribution used to determine how to distribute nodes randomly is based on the fact that about half the nodes in a skip list will be level 0 nodes, whereas a quarter of the nodes will be level 1 nodes, 12.

5% will be level 2 nodes, 5.75% will be level 3 nodes, and so on. All that s left to explain is how we determine how many levels will be used in the skip list.

The inventor of the skip list, William Pugh, a professor of Computer Science currently at the University of Maryland, worked out a formula in his paper that rst described skip lists (ftp://ftp.cs.umd.

edu/pub/skipLists/). Here it is, expressed in C# code:. (int)(Math.Ceiling(M .NET barcode standards 128 ath.

Log(maxNodes) / Math.Log(1 / PROB)) - 1);. where maxNodes is an approximation of the number of nodes that will be required and PROB is a probability constant, usually 0.25..

Skip List Implementation We need two classes for a skip list implementation: a class for nodes and a class for the skip list itself. Let s start with the class for nodes. The nodes we ll use for this implementation will store a key and a value, as well as an array for storing pointers to other nodes.

Here s the code:. public class SkipNod VS .NET Code 128 e { int key; Object value; SkipNode[] link; public SkipNode(int level, int key, Object value) {. ADVANCED DATA STRUCTURES AND ALGORITHMS this.key = key; this Code 128C for .NET .

value = value; link = new SkipValue[level]; } }. Now we re ready to b uild the skip list class. The rst thing we need to do is determine which data members we need for the class. Here s what we ll need:.

r r r r r r maxLevel: stores the maximum number of levels allowed in the skip list level: stores the current level header: the beginning node that provides entry into the skip list probability: stores the current probability distribution for the link levels NIL: a special value that indicates the end of the skip list PROB: the probability distribution for the link levels. public class SkipLis VS .NET barcode code 128 t { private private private private private private int maxLevel; int level; SkipNode header; float probability; const int NIL = Int32.MaxValue; const int PROB = 0.

5;. The constructor for the SkipList class is written in two parts: a Public constructor with a single argument passing in the total number of nodes in the skip list, and a Private constructor that does most of the work. Let s view the methods rst before explaining how they work:. private SkipList(flo Code 128 Code Set A for .NET at probable, int maxLevel) { this.probability = probable; this.

maxLevel = maxLevel; level = 0; header = new SkipNode(maxLevel, 0, null); SkipNode nilElement = new SkipNode(maxLevel, NIL, null) ; for(int i = 0; i <= maxLevel-1; i++) header.link(i) = nilElement;. Skip Lists } public SkipList(lo Code 128 Code Set C for .NET ng maxNodes) { this.New(PROB, (int)(Math.

Ceiling(Math.Log(maxNodes) / Math.Log(1/PROB)-1)); }.

The Public construct or performs two tasks. First, the node total is passed into the constructor method as the only parameter in the method. Second, the Private constructor, where the real work of initializing a skip list object is performed, is called with two arguments.

The rst argument is the probability constant, which we ve already discussed. The second argument is the formula for determining the maximum number of link levels for the skip list, which we ve also already discussed. The body of the Private constructor sets the values of the data members, creates a header node for the skip list, creates a dummy node for each of the header s links, and then initializes the links to that element.

The rst thing we do with a skip list is insert nodes into the list. Here s the code for the Insert method of the SkipList class:. public void Insert(i code128b for .NET nt key, Object value) { SkipNode[] update = new SkipNode[maxLevel]; SkipNode cursor = header; for(int i = level; i > = level; i--) { while(cursor.link[i].

key < key) cursor = cursor.link[i]; update[i] = cursor; } cursor = cursor.link[0]; if (cursor.

key = key) cursor.value = value; else { int newLevel = GenRandomLevel(); if (newlevel > level) { for(int i = level+1; i <= newLevel-1; i++) update[i] = header; level = newLevel; } cursor = new SkipNode(newLevel, key, value);.
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